Linq to SQL: Delete时遇到的问题

1.1、

在Linq to SQL中要删除一行记录，官方的例子教我这样做

Code1:

using (PubsDataContext pubsContent = new PubsDataContext())

{

pubsContent.Log = Console.Out;

Author author = pubsContent.Authors.Single(a => a.au_id == "111-11-1111");

pubsContent.Authors.DeleteOnSubmit(author);

pubsContent.SubmitChanges();

}